RSPCA London chief inspector Clare Dew said: “No-one noticed anything unusual on the bus before the monkey was discovered but we’ll be looking at CCTV and logs for scanning on and off to see if we can locate the person who left her on board.

“It was clearly intentional. This is clearly a direct result of the new legislation and is something we feared would happen. I’d be surprised if it’s the last primate we see being dumped.”

Following a check-up by a vet, Oyster was given a clean bill of health and has been transferred to a sanctuary where she will be introduced to a male companion.

The RSPCA is urging people struggling to care for pets or unable to secure licences not to abandon their animals but to seek advice from vets or animal charities.

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